/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package com.sun.org.apache.xml.internal.security.utils;

import javax.xml.XMLConstants;
import javax.xml.transform.TransformerException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import javax.xml.xpath.XPathFactoryConfigurationException;

import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * An implementation for XPath evaluation that uses the JDK API.
 */
public class JDKXPathAPI implements XPathAPI {

  private XPathFactory xpf;

  private String xpathStr;

  private XPathExpression xpathExpression;

  /**
   * Use an XPath string to select a nodelist.
   * XPath namespace prefixes are resolved from the namespaceNode.
   *
   * @param contextNode The node to start searching from.
   * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
   * @return A NodeIterator, should never be null.
   */
  public NodeList selectNodeList(
      Node contextNode, Node xpathnode, String str, Node namespaceNode
  ) throws TransformerException {
    if (!str.equals(xpathStr) || xpathExpression == null) {
      if (xpf == null) {
        xpf = XPathFactory.newInstance();
        try {
          xpf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, Boolean.TRUE);
        } catch (XPathFactoryConfigurationException ex) {
          throw new TransformerException("empty", ex);
        }
      }
      XPath xpath = xpf.newXPath();
      xpath.setNamespaceContext(new DOMNamespaceContext(namespaceNode));
      xpathStr = str;
      try {
        xpathExpression = xpath.compile(xpathStr);
      } catch (XPathExpressionException ex) {
        throw new TransformerException("empty", ex);
      }
    }
    try {
      return (NodeList) xpathExpression.evaluate(contextNode, XPathConstants.NODESET);
    } catch (XPathExpressionException ex) {
      throw new TransformerException("empty", ex);
    }
  }

  /**
   * Evaluate an XPath string and return true if the output is to be included or not.
   *
   * @param contextNode The node to start searching from.
   * @param xpathnode The XPath node
   * @param str The XPath expression
   * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
   */
  public boolean evaluate(Node contextNode, Node xpathnode, String str, Node namespaceNode)
      throws TransformerException {
    if (!str.equals(xpathStr) || xpathExpression == null) {
      if (xpf == null) {
        xpf = XPathFactory.newInstance();
        try {
          xpf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, Boolean.TRUE);
        } catch (XPathFactoryConfigurationException ex) {
          throw new TransformerException("empty", ex);
        }
      }
      XPath xpath = xpf.newXPath();
      xpath.setNamespaceContext(new DOMNamespaceContext(namespaceNode));
      xpathStr = str;
      try {
        xpathExpression = xpath.compile(xpathStr);
      } catch (XPathExpressionException ex) {
        throw new TransformerException("empty", ex);
      }
    }
    try {
      Boolean result = (Boolean) xpathExpression.evaluate(contextNode, XPathConstants.BOOLEAN);
      return result.booleanValue();
    } catch (XPathExpressionException ex) {
      throw new TransformerException("empty", ex);
    }
  }

  /**
   * Clear any context information from this object
   */
  public void clear() {
    xpathStr = null;
    xpathExpression = null;
    xpf = null;
  }

}
